The present invention relates to a method for the accelerated remediation of contaminated material and to a method of using a paddle therefor, and more particularly to a paddle connectable to, and extending outwardly from the periphery of, an elongate cylindrical drum. Remediation typically involves the degradation of contaminated material using chemical amendments.
Bioremediation in general involves the degradation of contaminated material, typically by the action of contaminate degrading aerobic bacteria. When practiced on a small scale, it is relatively easy to maintain the aerobic conditions required by the bacteria; it is much more difficult to do on a larger scale. Failure to maintain aerobic conditions throughout the contaminate material results in anaerobic decay of the material, which is much less efficient and much more time consuming than aerobic decomposition. This provides strong incentive to maintain aerobic reaction conditions at all times.
The biological degradation of hydrocarbons can be conducted employing specialized bacteria that utilizes hydrocarbons as their sole metabolic carbon source or as a co-metabolite. The bacteria produce enzymes, which catalytically crack the covalent carbon-hydrogen bonds of hydrocarbons so that the smaller resulting molecules may pass through the cell wall of the bacterial organism for nutrient. In some instances, the bacteria may produce enzymes, which crack a carbon bond on an alternate carbon source such as a carbohydrate. This same enzyme may also crack the hydrocarbon. This is called co-metabolism.
In addition to a carbon source, most living organisms require a balance of other nutrients such as nitrogen, phosphorus, various minerals in micro quantities, etc. to efficiently metabolize and reproduce. Any specific nutrient that is deficient in a given biological system will limit the efficiency of that system. This is akin to the xe2x80x9cbasic 4 food groupsxe2x80x9d idea of human nutrition which includes protein as a nitrogen source, carbohydrate as a carbon source, dairy as a fat or fatty acid source plus phosphorus and a large number of vegetables as a vitamin and mineral source. Although bacterial requirements may be different from humans, a balanced nutritional system is required for optimal bacterial activity.
There are thousands of identified sites in the United States containing hazardous wastes. For most of these sites, the recognized methods for closure are:
1. Cap and store-in-place
2. Removal to an approved hazardous waste landfill.
3. Solidify in place with fixation chemicals
In addition to the methods generally known, many industrial plants have used biological solutions to effect closures. Quite a few biological cleanups took place prior to the effect of the RCRA and TSCA legislation. Now under the formal guidelines of current hazardous waste regulation, use of biological treatment can offer an economical alternative to the methods listed above.
Biological treatment of hazardous waste chemicals can take the following forms:
1. Treatment of industrial wastewater through biological oxidation and/or reduction under an NPDES permit.
2. Treatment of on site chemicals through controlled release to an NPDES-permitted system (many states allow this through a temporary permit amendment).
3. Treatment of leachates collected under hazardous waste sites. In some cases a cone of depression can be created to leach organics out at a rapid rate.
4. Land farm of sludges and solid-containing organics. Land farming is of principle interest due to the large numbers of area sites with contaminated sludges and soils.
A key issue in a hazardous waste site closure is permitting land farms. Often obtaining such a permit is not feasible under existing regulations. In most cases, those regulations were intended to address new land farms. Land farming is a biochemical process which operates at low biological reaction rates. The variables controlling total cleanup time in a land farm are initial substrate concentrations, desired treatment levels, area available for land farm and turnaround time to dispose of decontaminated sludge or soil. Many hazardous waste sites could be successfully land farmed in 6-12 months, after pilot work is complete.
The actual protocol for remediating a particular site should be established for each site by a combination of pilot testing and practice. A typical protocol for remediating a hazardous waste site would be as follows:
1. CHARACTERIZATION OF THE SITE
This includes additional soil borings, groundwater monitoring and chemical analyses to determine the site contamination characteristics.
2. CHARACTERIZATION OF THE ORGANICS AS TO BIODEGRADABILITY
This is usually researched into the treatability of chemicals found in the site.
3. CHARACTERIZATION OF THE SOIL
The soil must be analyzed for pH, macronutrients (N,P,K), micronutrients (usually trace metals), permeability, moisture content and other conditions which will determine its suitability for land farming.
4. CRITERIA FOR SUCCESSFUL LAND TREATMENT
A chemical protocol is established to allow monitoring of the land farm. This is a two-tier protocol consisting of:
A. Control analyses to allow quick determination of treatment progress during the land farming.
B. Objective toxicity testing to be used when control analyses indicates that the treatment is complete. This includes all testing for leachate priority pollutants.
5. BENCH SCALE LAND FARM TREATMENT
Using the site characteristics, the land farm is simulated and efficiency of the treatment is proven. Samples of decontaminated soil and sludge may be presented for reference analyses.
6. DESIGN OF LAND FARM TREATMENT
The consultant and land farm specialists designate the portion of the closure site to be used for the land farm and design excavation schedules, aeration and mixing techniques, irrigation method, run-off collection, and decontaminated soil removal and disposal method.
7. IMPLEMENTATION OF LAND FARM TREATMENT
Beginning with a surface treatment of the site to be used, the land farm is begun. After control testing shows a desired level of treatment, toxicology tests are made. The soil may then be decontaminated and removed, if desired. Land farming is then usually continued in 12xe2x80x3 lifts.
8. CLOSURE
Decontaminated sludges and soils are removed to a nonhazardous waste landfill or landfilled on-site.
The above steps are difficult and timely in their performance. They are also extremely costly to perform for the end user.
There are known machines for physically mixing materials in the field such as compost to maintain aerobic conditions. An example is U.S. Pat. No. 4,360,065 to Jenison et al. The Jenison cultivator comprises a horizontal rotating drum having a plurality of cultivator blades in two helical rows. As the drum is rotated, the blades travel edgewise through a pile of contaminated material to move the material sideways and pile it in a generally triangular pile. The ""065 patent further describes other contaminated machines such as the Scarab, sold by Scarab Manufacturing and Leasing, Inc. of White Deer, Tex. U.S. Pat. No. 3,369,797 to Cobey describes a compost turner and windrow forming machine having a transversely mounted rotating drum for the turning of compost piles and the redepositing of the turned up material in a windrow. Yet another contaminated apparatus is described in U.S. Pat. No. 4,019,723 to Urbanczyk. The ""723 patent describes a mobile apparatus for manure which moves a rotating drum over masses of inoculated manure to flail it, mix it, cool it and aerate it, while moistening the particles as the same time. After being conditioned and moisturized, the material is formed into a pile by a rear outlet opening. As with the Cobey apparatus, the flails mounted on the drum of the Urbanczyk machine travel edgewise through the contaminated material for flailing and mixing. U.S. Pat. No. 4,478,520 also to Cobey describes a compost turning machine which straddles a compost windrow while carrying a rotating drum for turning the contaminated material. The ""520 apparatus additionally has an adjuster auger system outboard of the rotating drum to collect additional material and deposit it in the path of the rotating drum. This is the Cobey machine referred to earlier.
A need therefore exists for a method of remediation which will overcome the problems associated with the above described prior art methods by substantially eliminating the contaminants from contaminated material in an effective, efficient and accelerated manner.
Applicants have met the above-described existing needs and have overcome the above-described prior art problems through the invention set forth herein.
In one form of the invention, a method of using an apparatus is provided for the accelerated remediation of treated contaminated material. Treating of the contaminated material with at least one chemical amendment, with or without at least one biological amendment, can occur prior to, and/or during, and/or subsequent to, microenfractionating of the contaminated material. The chemical amendment can be at least one chemical reducing agent with or without at least one chemical oxidizing agent. For example, a contaminated material can be treated with at least one chemical amendment comprising a chemical reducing and/or oxidizing agent to form a treated contaminated material prior to microenfractionation of thereof. Then, an air stream is generated at a velocity sufficient for entraining the treated contaminated material therein, and the treated contaminated material is entrained in the air stream, and the treated contaminated material is microenfractionated under conditions sufficient to form a microenfractionated treated contaminated material such that subsequent accelerated remediation is provided under conditions sufficient for conducting said accelerated remediation. Alternatively, the chemical amendment(s) can be added during, or subsequent to, microenfractionating of the contaminated material. In any of the above-described methods, the accelerated remediation of the treated contaminated material can be facilitated.
The chemical amendment can also comprise at least one chemical reducing agent which is in the form of a liquid or a solid, preferably an aqueous solution, which is capable of acting as a chemical reducing agent for remediation or bioremediation purposes, particularly in the microenfractionation of contaminated materials of the present invention. These types of chemical amendments are particularly useful in the dehalogenation of halogenated hydrocarbons such as the difficult to remediate chlorinated hydrocarbons.
The chemical amendment of this invention can comprise a chemical reducing agent. Preferably, the chemical reducing agent comprises a metallic reducing agent. Preferably, the metallic reducing agent comprises a zero valent metallic compound. More preferably, the metallic reducing agent is a zero valent metallic compound comprising iron, zinc, tin, aluminum, manganese or other similar zero valent metallic compounds. Most preferably, the chemical reducing agent comprises a zero valent iron compound.
An activating agent can also be added to the chemical reducing agent to make the remediation with the chemical reducing agent more effective and/or efficient. Such activating agents are typically acidic activating agents, preferably organic acid acidic activating agents such as acetic acid, or inorganic acidic materials such as hydrochloric acid, phosphoric acid, or nitric acid. Other acidic activating agents may include aliphatic alpha-hydroxycarboxylic acids of the type RCHOHCOOH and the corresponding beta-hydroxycarboxylic acids RCHOHCH2COOH, complexing agents such as ethylenediaminetetraacetic acid (EDTA), nitrolotriacetic acid (NTA) and diethylenediamine-pentaacetic acid (DPTA) and amines, hydroxyl containing amines such as mono-, di- and triethanolamine and diamines, triamines, polyamines having complexing properties. Exemplary alpha- and beta-hydroxy carboxylic acids are glycolic acid, lactic acid, glyceric acid, xcex1, xcex2-dihydroxybutyric acid, xcex1-hydroxy-butyric acid, xcex1hydroxy-isobutyric acid, xcex1-hydroxy-n-valeric acid, xcex1-hydroxy-isovaleric acid, xcex2-hydroxy butyric acid, xcex1-hydroxy-isobutyric acid, xcex2-hydroxy-n-valeric acid, xcex2-hydroxy isovaleric acid, erythronic acid, threonic acid, trihydroxy-isobutyric acid and saccharinic acids and aldonic acids, such as gluconic acid, galactoni acid, talonic acid, mannonic acid, arabonic acid, ribonic acid, xylonic acid, lyxonic acid, gulonic acid,idonic acid, altronic acid, allonic acid, ethenyl glycolic acid, and xcex2-hydroxy-isocrotonic acid. Also useful are organic acids having two or more carboxylic groups, and no or from one to ten hydroxyle groups, such as oxalic acid, malonic acid, tartaric acid, malic acid, and citric acid, ethyl malonic acid, succinic acid, isosuccinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, maleic acid, fumaric acid, glutaconic acid, citramalic acid, trihydroxy glutaric acid, tetrahydroxy adipic acid, dihydroxy maleic acid, mucie acud, mannosaccharic acid, idosaccharic acid, talomucie acid, tricarballylic acid, aconitic acid, and dihydroxy tartaric acid.
The chemical amendment can also comprise at least one chemical oxidizing agent which is in the form of a liquid or a solid, preferably an aqueous solution. Preferably, the chemical oxidizing agent can comprise a peroxide, a permanganate, a nitrate, a nitrite, a peroxydisulfate, a perchlorate, a sulfate, chlorate, a hypochlorite, an iodate, a trioxide, a peroxybenzoic acid, an oxide, an iodic acid, a nitric acid, a periodic acid, a peracetic acid, a hydantoin, a triazinetrione, a hydroxide, a percarbonate, a superoxide, an isocyanate, an isocyanic acid, a bromanate, a biiodate, a bromate, a bromate-bromide, a molybdic acid, a dichromate, a chromate, a periodate, a chlorite, an iodate, or a perborate. More preferably, the chemical amendment can comprise any one of the following: aluminum nitrate, ammonium dichromate, ammonium nitrate, ammonium peroxydisulfate, ammonium permanganate, aquaquant sulfate, ammonium perchlorate, microquant sulfate, ammonium peroxydisulfate, spectroquant nitrate, barium bromate, barium chlorate, barium nitrate, barium perchlorate, barium permanganate, barium peroxide, cadmium nitrate, 1-bromo-3chloro-5,5dimenthylhydantoin bismuth nitrate, calcium hypochlorite, calcium iodate, calcium nitrate, ceric ammonium nitrate, ceric sulfate, calcium chlorate, calcium chlorite, calcium hypochlorite, calcium perchlorate, calcium permanganate, calcium peroxide, cerous nitrate, chloric acid, chromium trioxide, chromium nitrate, cobalt nitrate, copper chlorate, cupric nitrate, halane (1,3, dichloro-5,5-dimenthylhydandoin),3-chloroperoxybenzoic acid, ferric nitrate, hydrogen peroxide, guanidine nitrate, iodic acid, lanthanum nitrate, lead dioxide, lead nitrate, lead oxide, lead perchlorate, lithium nitrate, lithium perchlorate, lithium hypochlorite, lithium chlorate, lithium peroxide lithium, perchlorate, magnesium bromate, magnesium chlorate, magnesium peroxide, magnesium nitrate, mercuric nitrate, mercurous nitrate, mercurous chlorate, manganese dioxide, mono-(trichloro)-tetra-(monopotassium dichloro)-penta-xcex1-triazinetrione, magnesium perchlorate, nitric acid,nickel nitrate, mercurous nitrate, periodic acid, peracetic acid,perchloric acid solutions, Class II and III (depending upon centration), potassium peroxide, potassium superoxide, potassium biiodate, potassium bromate, potassium bromate-bromide, phosphomolybdic acid, phenylmercuric nitrate, potassium hydroxide, potassium iodate, potassium dichromate, potassium nitrate, potassium nitrite, potassium chromate, potassium dichloro-xcex2-triazinetrione (potassium dichloroisocyanate), potassium dichromate, potassium chlorate, potassium percarbonate, potassium perchlorate, potassium periodate, potassium permanganate, potassium persulfate, silver peroxide, sodium bromate, sodium carbonate peroxide, sodium dichloro-xcex2-triazinetrione (sodium dichloroisocyanate) silver nitrate, silver oxide, silver perchlorate, sodium chlorite, sodium chlorate, sodium nitrate, sodium iodate, sodium dichromate, sodium nitrate, sodium perborate, sodium perborate (anhydrous) sodium perchlorate, sodium percarbonate, sodium perchlorate monohydrate, sodium periodate, sodium nitrite, sodium persulfate, sodium permanganate, sodium peroxide, strontium nitrate, strontium perchlorate, strontium peroxide, thorium nitrate, trichloroisocyanic acid, zinc nitrate, thallic nitrate, uranyl nitrate, urea peroxide, yttrium nitrate, zinc bromanate, zinc chlorate, zinc permanganate, and zinc peroxide.
The contaminated material can comprise nitrated and/or chlorinated hydrocarbons including nitrated and/or chlorinated polycyclic materials, nitrated and/or chlorinated heterocyclic materials, and nitrated and/or chlorinated aliphatic materials. Exemplary contaminated compounds include chlorinated pesticides, TNT, and RDX.
Preferably, the accelerated remediation reaction is conducted aerobically or abiotically. The reaction can also be conducted methanogenically.
Generally, the means for generating a treated contaminated material entraining air stream at a predetermined velocity comprises an elongate drum having a longitudinal axis, first and second end portions, and a center portion. The drum is rotatable about its longitudinal axis at a predetermined rotational speed, and means extending outwardly from the drum are provided for generating the treated contaminated material entraining air stream. Preferably, the treated contaminated material entraining air stream comprises a plurality of air currents, and the air current generating means comprises a plurality of paddles extending outwardly from the cylindrical outer surface of the drum. Typically, each paddle comprises a base portion connected to the drum, and a blade portion. Each blade portion has a major surface oriented for generating at least one the air current having a sufficient velocity for entraining and transporting treated contaminated material upwardly of the rotating drum when the drum is rotated at the predetermined rotational velocity.
The treated contaminated material entraining air stream preferably comprises a plurality of intersecting air currents. Each of the intersecting air currents has a sufficient velocity for entraining and transporting a portion of the treated contaminated material upwardly of the air stream generating means. More specifically, the means for generating a plurality of intersecting air currents comprises a plurality of end paddles extending radially outwardly from the first and second end portions of the drum. Each end paddle can comprise a base portion connected to the drum and a blade portion. In this instance, the blade portion has a major surface oriented relative to the drum for generating an air current directed upwardly of the drum and transversely toward the center portion of the drum when the drum is rotated at the predetermined rotational speed. It also has a plurality of center paddles extending radially outwardly from the center portion of the cylindrical outer surface. Each center paddle comprises a base portion connected to the drum, and a blade portion having first and second major surfaces. The first and second major surfaces are oriented relative to the drum for generating an air current directed upwardly and rearwardly of, and transversely toward the first and second end portions of the drum respectively when the drum is rotated at the predetermined rotational speed. In use, the air currents generated by the end and center paddles intersect and combine to form the treated contaminated material entraining air stream for microenfractionating the treated contaminated material.
In a preferred embodiment, the treated contaminated material entraining air stream comprises a vortex-type air stream which transports the entrained treated contaminated material in a generally circular path. In this case, the end and center paddles can extend radially outwardly from the drum so that they are arranged in a plurality of helical longitudinal row. Also, the drum can further comprise first and second transition portions disposed between the center portion and the first and second end portions respectively. The first and second transition portions of the drums having a plurality of end paddles and a plurality of center paddles extending radially outwardly therefrom.
In another form of the invention, a method of accelerated remediation of treated contaminated material is provided. This method comprises the steps of (a) treating the treated contaminated material with chemical biological amendments for facilitating accelerated remediation thereof, (b) providing an entraining air stream having a sufficient velocity for entraining the treated contaminated material therein, (c) entraining the treated contaminated material in the air stream, (d) microenfractionating the treated contaminated material, and (e) discharging the microenfractionated treated contaminated material from the air stream so that the treated contaminated material will be acceleratedly remediated. The microenfractionating step preferably comprises homogenization and aeration of the treated contaminated material. The entraining air stream preferably comprises providing an entraining air stream including a plurality of upwardly and transversely flowing, intersecting air currents, and more preferably comprises a vortex-like entraining air stream. Typically, the step of providing an entraining air stream includes the step of rotating a drum assembly at a rotational speed sufficient for generating the entraining air stream. The drum assembly can include means for generating this plurality of intersecting air currents when the drum assembly is rotated.
In one preferred method, the treated contaminated material is contaminated with a hydrocarbon material, and the accelerated remediation of the treated contaminated material comprises accelerated chain scission of the hydrocarbon material. In another case, when the treated contaminated material is contaminated with hydrocarbon material, the accelerated remediation, typically employing chemical reduction. If the hydrocarbon contaminant is halogenated, a halogen will also be produced. A further instance is where the treated contaminated material is contaminated with hydrocarbon material, and the accelerated remediation comprises reduction of the total hydrocarbon material in the treated contaminated material.
In general, at least about 70%, preferably at least about 80%, more preferably at least about 90%, and most preferably at least about 95% of the accelerated remediation of the treated contaminated material is completed within 150 days, preferably within 120 days, more preferably within 90 days, and most preferably within 60 days. Moreover, the volume of treated contaminated material which is acceleratedly remediately treated by the method of the present invention is generally at least about 1500 cubic yards, preferably at least about 2000 cubic yards more preferably at least about 2500 cubic yards, most preferably at least about 3000 cubic yards, per day per apparatus. This is particularly significant in the case of chlorinated contaminates since most prior art systems cannot remediate these compounds even after years of trying to treat same.
The method of the subject invention produces high surface area treated contaminated microenfractionated material. The surface area of the treated contaminated non-microenfractionated material can be increased, after the microenfractionating step, as compared to the surface area of the treated contaminated non-microenfractionated material, by a factor of at least about 1xc3x97106, preferably at least about 2xc3x97106, more preferably at least about 3.5xc3x97106, and most preferably at least about 5xc3x97106. More specifically, the subject method can further include the step of discharging the microenfractionated treated contaminated material from the air stream and redistributing it throughout a soil matrix. In this manner, the surface area of the microenfractionated treated contaminated material is substantially increased. This is especially important when dealing with clay type soils.
Most prior art remediation processes cannot be conducted at ambient temperatures below 10 degrees C. However, when the method of the subject invention is employed, the aforementioned high degree of accelerated remediation can be maintained at an average ambient temperature which is not more than about 10 degrees C., preferably not more than about 7 degrees C., more preferably not more than about 3 degrees C., and most preferably not more than about 1 degree C.
One reason why the accelerated remediation of this invention can be conducted at the low ambient temperature conditions described in the preceding paragraph herein, is that the subject reaction is generates a more substantial amount of exothermic heat than known prior art remediation processes. Thus, the accelerated remediation is preferably conducted at an exothermic temperature measured within the contaminated material of at least about 5 degrees, and more preferably at least about 10 degrees, higher than an average ambient air temperatures of from about zero up to about 10 degrees C.
As for the treatment of the contaminated material with the chemical amendments, it is preferred that they are dispersed throughout the redistributed microenfractionated treated contaminated material thereby facilitating accelerated remediation.
Other preferred embodiments of the subject method include (a) locating an impervious undercover below the treated contaminated material prior to the microenfractionating step thereby preventing the chemical amendments from leaching into soil underlying the treated contaminated material, and (b) a cover over the microenfractionated treated contaminated material, the cover allowing substantial solar radiation to pass there through and into the microenfractionated treated contaminated material, thereby facilitating the accelerated remediation and preventing moisture from soaking the microenfractionated treated contaminated material and to prevent moisture evaporation from the microenfractionated treated contaminated material.